Just my 2 cents, but trying to remove enough BH and GSF by seining is nearly pointless. Trying to get it done with a short seine would be like trying to pull weeds by hand in an overgrown pond. Great exercise but does not accomplish much. Your only real option if you have an abundance those fish would be to dry it out or use rotenone or hydrated lime as posted earlier. You would be better off sampling with a minnow seine to see what you have and restocking with bigger fish as is; if killing the fish is out.

-HH